In the format conversion domain, more than one technique exists and, in all of these techniques, a readjustment of the image size is carried out. These different techniques are shown in FIGS. 1(a) to 1(d). FIG. 1(a) shows a source image of format 16:9 to be converted into a final image of format 4:3. A first technique illustrated by the FIG. 1(b) consists in applying to the source image an anamorphic distortion that compresses it in the sense of its width. The final image is then deformed. A second technique shown by FIG. 1(c) consists in adding black vertical and/or horizontal bands around the source image to compensate the differences in size between the source image and the final image. In the example of FIG. 1(c), horizontal black bands are added above and below the source image. This technique is commonly called “letterbox”. In the case of vertical black bands, the technique is called “pillarbox”. A third technique shown by FIG. 1(d) consists in displaying only a part of the source image by cropping the source image on the sides or at the upper and lower edges. This technique is known as “cropping”.
In all of these techniques, the readjustment of the image size leads to an under-exploitation of the surface of the screen displaying the final image (“pillarbox” or “letterbox” technique) or a deformation of the image (anamorphic distortion) or a loss of useful content that can be severe (“cropping”).
Moreover, the insertion of an information banner, such as a publicity banner, in an image is commonly performed by placing the banner on a part of the image, for example the lower part of the image. This banner is possibly displayed in transparency on the image to limit the loss of visual information contained in the image. This insertion of an information banner is usually carried out outside of the context of format conversion. If the two operations are carried out successively without combining them, that is to say that an information banner is inserted in a cropped image following a format conversion, the loss of information is then accentuated.